1. Field of the Invention
The present invention relates to a method of evaluating breast cancer, a breast cancer-evaluating apparatus, a breast cancer-evaluating method, a breast cancer-evaluating system, a breast cancer-evaluating program and recording medium, which utilize the concentration of amino acids in blood (plasma).
2. Description of the Related Art
The number of deaths from breast cancer in Japan in 2003 is 67 males and 8882 females, which accounts for 18.3% of deaths from all cancers, and the number of deaths from breast cancer ranks fifth in females among the deaths from cancers.
In general, breast cancer is considered to have good prognosis as compared with cancers of other organs. As the reasons, there may be mentioned that development and progress of breast cancer is often gentle compared to those of other cancers, that in many cases, eradication is possible by appropriate treatment, that even when breast cancer is in progress or when breast cancer has recurred and is difficult to eradicate, there still are effective treatment methods in response to symptoms, and the like. As a result, the five-year survival rate and the ten-year survival rate in breast cancer are favorable as compared with those in other cancers. Specifically, the five-year survival rate of early (stages I and II) breast cancer is 80% or higher, and particularly, the five-year survival rate of stage I breast cancer (the diameter of tumor is less than 2 centimeters, and metastasis outside breast does not occur) is about 90%.
Breast cancer is one of cancers on which research is being conducted in a global scale, and development of new medicines or new treatment methods against breast cancer is in progress.
However, the frequency of breast cancer has been increasing in Japan, and at present, about 36,000 patients per year are diagnosed as breast cancer (nationwide survey in 1999). Furthermore, the survival rate of progressive cancer undergoes a decrease, and specifically, the five-year survival rate of stage IV breast cancer is about 10%. Therefore, early detection is important for the healing of breast cancer.
Here, diagnosis of breast cancer is achieved mainly by self examination, breast palpation and visual inspection, diagnostic imaging by mammography, CT (computer tomography), MRI (magnetic resonance imaging), PET (positron emission computerized-tomography) or the like, and needle biopsy.
However, self examination, palpation and visual inspection, and diagnostic imaging do not serve as definitive diagnosis. In particular, self examination is not effective to the extent of lowering the rate of deaths from breast cancer. Furthermore, self examination does not enable the discovery of a large number of early cancers, as regular screening by a mammographic examination does. In early breast cancer, there is a concern that self examination, palpation and visual inspection, or diagnostic imaging is even poorer in both detection sensitivity and detection specificity. Diagnostic imaging by mammography also has a problem of exposure of test subject to radiation or overdiagnosis. Diagnostic imaging by CT, MRI, PET or the like also is problematic to be carried out as mass screening, from the viewpoints of facilities and costs.
On the other hand, needle biopsy serves as definitive diagnosis, but is a highly invasive examination, and implementing needle biopsy on all patients who are suspected of having breast cancer as a result of diagnostic imaging, is not practical. Furthermore, such invasive diagnosis as needle biopsy gives a burden to patients, such as accompanying pain, and there may also be a risk of bleeding upon examination, or the like.
Generally, it is conceived that in many cases excluding self examination, examination of breast cancer makes test subjects hesitating. Therefore, from the viewpoints of a physical burden and a mental burden imposed on test subjects, and of cost-benefit performance, it is desirable to narrow down the target range of test subjects with high possibility of onset of breast cancer, and to subject those people to treatment. Specifically, it is desirable that test subjects are selected by a method accompanied with less mental suffering or a less invasive method, the target range of the selected test subjects is narrowed by subjecting the selected test subjects to needle biopsy, and the test subjects who are definitively diagnosed as having breast cancer are subjected to treatment.
Incidentally, it is known that the concentrations of amino acids in blood change as a result of onset of cancer. For example, Cynober (“Cynober, L. ed., Metabolic and therapeutic aspects of amino acids in clinical nutrition. 2nd ed., CRC Press.”) has reported that, for example, the amount of consumption increases in cancer cells, for glutamine mainly as an oxidation energy source, for arginine as a precursor of nitrogen oxide and polyamine, and for methionine through the activation of the ability of cancer cells to take in methionine, respectively. Proenza, et al. (“Proenza, A. M., J. Oliver, A. Palou and P. Roca, Breast and lung cancer are associated with a decrease in blood cell amino acid content. J Nutr Biochem, 2003. 14(3): p. 133-8.”) and Cascino (“Cascino, A., M. Muscaritoli, C. Cangiano, L. Conversano, A. Laviano, S. Ariemma, M. M. Meguid and F. Rossi Fanelli, Plasma amino acid imbalance in patients with lung and breast cancer. Anticancer Res, 1995. 15(2): p. 507-10.”) have reported that the amino acid composition in plasma in breast cancer patients is different from that of healthy individuals.
However, there is a problem that the development of techniques of diagnosing the presence or absence of onset of breast cancer with a plurality of amino acids as explanatory variables is not conducted from the viewpoint of time and cost and is not practically used.